微型磁通门的优化分析与性能测试

对铁芯结构的改进有利于满足微型磁通门传感器降低功耗的要求,但不同的拓扑结构所取得的效果不同,为此对铁芯结构进行了优化分析,并采用MEMS工艺制备了不同铁芯结构的微型磁通门进行性能测试与对比验证.测试结果表明,优化后的多孔铁芯结构能更好的降低微型磁通门传感器的功耗与噪声,提高灵敏度,改善器件的整体性能.     

新型环形同点单铁芯双分量磁通门传感器

双分量磁通门传感器在金属磁记忆检测中得到广泛使用,且使用的双分量磁通门传感器为双铁芯式跑道型设计的磁通门传感器。由于传感器中的双铁芯磁参数不一致、铁芯不闭合的原因,产生变压器效应,形成了测量噪声。双分量磁通门通常由两个磁通门传感器平行放置而成。因此,由于传感器铁芯参数,线圈参数不可能完全一致所造成的传感器之间的一致性差,而且双分量或多分量磁通门传感器存在着几何中心不重合的问题。本文研究设计了新型双分量磁通门传感器,采用环形铁芯设计,直接应用单铁芯调理双方向的磁通门信号,改善了双分量传感器的一致性差、几何中心不同点的问题,有效的抑制了变压器噪声,提高了磁通门传感器的测量中的测量准确度,减少了测量误差。     

地磁相对记录用低噪声磁通门磁力仪

针对地磁相对记录要求观测仪器具有高分辨力、低噪声和长期稳定性的特点,抑制外界温度对传感器输出的影响,获得较低的温度系数,研制的磁通门传感器采用高导磁率坡莫合金作为磁芯材料,激励线圈直接缠绕在高塑性、较高持久蠕变强度的环形合金骨架上,感应线圈和补偿线圈缠绕在低温度系数的玻璃钢骨架上.采用交变模拟信号处理电路、深度负反馈网...     

基于Magnet-MATLAB的微型磁通门联合仿真研究

针对Magnet在微型磁通门仿真分析时时间过长的问题,提出了一种将Magnet与MATLAB联合进行仿真分析的方法.基于Magnet建立磁通门探头3D模型,经仿真计算,得到被测磁场对应的感应线圈磁通;联合MATLAB将得到的感应线圈磁通转换为等效的小电流,经与激励电流叠加后,通过软件Flux提供的公式分别计算出受被测磁场影响下感应线圈磁通的变化情况;总磁通对时间求导,获得感生电压.在微型跑道型铁芯磁通门条件下,通过对Magnet仿真与Magnet-MATLAB联合仿真的计算结果比较表明:当外磁场小于5 μT时,2种仿真磁通门输出信号最为接近;与对全模型采用Magnet仿真计算用时超过30 h相比,联合仿真计算时间大幅减小,不超过10 min.     

微型磁通门铁芯结构的拓扑分析与优化

多孔铁芯有利于满足微型磁通门传感器降低功耗的要求,但不同的拓扑结构所取得的效果不同,对多孔铁芯结构进行了拓扑分析与针对性优化,并采用微机电系统(MEMS)工艺制备了不同铁芯结构的微型磁通门进行性能测试与对比验证.实验结果证明:优化后的铁芯结构能更好地降低微型磁通门传感器功耗,提高器件整体性能.     

一种高空间分辨率遥感影像信噪比测定方法

信噪比是用来评价遥感影像质量一个重要的辐射特性参数。通过合适的方法精确地测定出遥感影像对应的信噪比参数,可以帮助数据提供者或用户更好地预测和提高遥感影像的信息提取能力。现有的信噪比测定方法大多基于中低空间分辨率遥感影像进行,并不能很好地适用于高空间分辨率遥感影像。针对现有信噪比测定方法的这一局限性,从高空间分辨率遥感影像本身特点出发,通过自适应地划分DN值子区间,以一定百分比最小局部标准差的平均值估算每一DN值子区间对应的噪声大小,进而估算每一DN值子区间对应的信噪比。该方法充分考虑了高分遥感影像内空间细节信息、边缘信息以及纹理信息较强而使得均值区域很难获取的特点。研究表明:改进的方法对于估算高分遥感影像信噪比具有较好的适用性。     

磁通门测量地磁信号的数字化分析

针对现有的磁通门信号处理电路仍以模拟元件为主,电路较为复杂的缺点,提出了一种以数字信号处理器(DSP)为主的信号处理系统,优化磁通门传感器的结构,提高了磁通门传感器的抗干扰能力.根据双磁芯磁通门的基本原理,建立了磁通门数学模型并采用Simulink信号处理模块模拟DSP对磁通门输出信号进行处理;针对双磁芯磁通门上、下磁芯不一致产生的磁通门信号噪声,采用带通滤波方法进行了滤波,仿真结果与理想状态下双铁芯磁通门的输出一致,系统分辨力达到3 nT.通过实验数据与仿真数据的对比,验证了DSP信号处理系统的可行性.     

Two-axis micro fluxgate sensor on single chip

We present a two-axis micro fluxgate sensor on single chip for electronic compassing function. To measure X- and Y-axis magnetic fields, functional two fluxgate sensors were perpendicularly aligned and connected each other. The fluxgate sensor was composed of square-ring shaped magnetic core and solenoid excitation and pick-up coils. The solenoid coils and magnetic core were separated by benzocyclobutane which had high insulation and good planarization characters. Copper coil patterns of 10 μm width and 6 μm thickness were electroplated on Ti (300 Å)/Cu (1,500 Å) seed layers. 3 μm thick Ni_0.8Fe_0.2 (permalloy) film for the magnetic core was also electroplated under 2,000 gauss. Excellent linear response over the range of ?100 μT to +100 μT was obtained with the sensitivity of ～280 V/T. Actual chip size was 3.1×3.1 mm². The sine and cosine signals of two-axis fluxgate sensor had a good function of azimuth compass.     

MEMS micro fluxgate sensors with mutual vertical excitation coils and detection coils

As a classic Earth magnetic field sensor, fluxgate magnetic sensors have great potential applications in many fields. This paper presents a new 3D micro-solenoid fluxgate magnetic sensor based on the MEMS technique. The excitation coils were placed vertically to the detection coils on the chip plane, around a rectangular shaped magnetic core. Polyimide was used to insulate coils and magnetic core. Width of copper conductor lines is 50 μm, and line space is 50 μm. The design of such fluxgate magnetic sensor followed second harmonic signal selecting method. Phase-lock amplifier was used to get second harmonic signal output by detection coils. The linear range of 0–80 μT with sensitivity of 6.7 V/T was achieved from the fabricated sensor with excitation current of 430 mA and the operational frequency of 40 KHz. As the excitation current was 470 mA, linear range of 0–50 μT with sensitivity of 21.7 V/T was achieved.     

Improved performance of the micro planar double-axis fluxgate sensors with different magnetic core materials and structures

As a classic weak magnetic field sensor, the fluxgate sensors have great potential application in many fields. This paper presents four kinds of the micro planar double-axis fluxgate sensors based on the MEMS technologies, which have different core materials and core structures. The core materials include electroplated permalloy, Co-based amorphous ribbon and Fe-based amorphous ribbon, and the core structures include single-layer open magnetic loop structure and double-layer closed magnetic loop structure. The sensor with closed double-layer Fe-based ribbon core exhibits a best sensitivity of 238 V/T due to reducing the magnetic flux leakage. The results show that the magnetic core with closed magnetic loop, high permeability and high saturation induction density will help increase the sensitivity of the micro double-axis fluxgate sensor.     

微型磁通门性能指标的综合测试与分析

对铁芯结构的改进有利于提高微型磁通门传感器的性能,采用MEMS工艺制备了多孔铁芯结构微型磁通门,并对所制备的微型磁通门进行主要的工作参数和性能指标的综合测试,分析了激励电流和激励频率对灵敏度、线性范围、噪声、剩磁误差等性能指标的影响规律.对实验结果的分析结论为传感器选择合适工作参数提供了数据支持.     

被动微波遥感数据超分辨率增强与混合像元分解研究综述

星载被动微波遥感数据以其全天候、穿透性以及不受云干扰等特点,在全球变化研究领域取得了广泛的应用,然而其较低的空间分辨率,限制了后期地物参数的反演精度。对国内外被动微波遥感数据空间分辨率提高方法进行介绍,重点介绍了基于图像处理技术的超分辨率增强和混合像元分解方法。通过对两类方法的介绍和评价,展望被动微波遥感数据混合像元分解方法的研究前景。被动微波遥感数据空间分辨率的有效提高,可以为更多的研究和应用领域服务。     

Physical‐based spatio‐temporal resolution enhancement of scalar data for fluid visualization

We present a method that improves the spatio‐temporal resolution of original data with fluid scalar data. The basis of the method, velocity estimation, is constructed to be inverse and optimized problem. We reduce the calculation cost through convex optimization and make the velocity field more accurate by coupling with Navier–Stokes equations. The spatial resolution receives significant enhancement by applying advection on original data with higher‐resolution velocity field data generated by our method. The temporal resolution is improved by generating intermediate velocity fields through the solution of Navier–Stokes equations. In this paper, we demonstrate that the accuracy of our velocity estimation method is clearly better than that of optical flow methods and the enhanced data show an attractive performance in fluid visualization. Copyright © 2016 John Wiley & Sons, Ltd.     

Improved micro fluxgate sensor with double-layer Fe-based amorphous core

A rapid manufacturing process for the micro solenoid fluxgate sensor integrating multilayer amorphous ribbon core has been established, which combines the micro assembling method and the MEMS technologies. We select Fe-based amorphous soft magnetic ribbons for core materials and have fabricated the micro fluxgate sensors by MEMS technologies, with single-layer core and double-layer core respectively. The micro fluxgate sensors with double-layer core show the advantageous to that with single-layer core and exhibit sensitivity of 1089.2 V/T at excitation current of 120 mA rms, wide linear range of ?900 to 900 μT and power consumption of 24.48 mW. The noise power density of the single core fluxgate sensor is 2.48nT/Hz^1/2@1 Hz.     

Characterization of flexible RF microcoils dedicated to local MRI

In magnetic resonance imaging (MRI), the electrical performance of the RF coil is critical to achieve sufficient signal to noise ratio (SNR), especially when microscopic structures [about (100 μm)³] have to be observed. In this field of application, we have developed a device (microcoil) based on the original concept of monolithic resonator, dedicated to superficial region imaging (human skin) or small animal imaging. This paper presents the developed process based on micromoulding. Flexible thin films of polymer have been used as dielectric substrate so that the microcoil could be form-fitted to non-plane surfaces. First, electrical characterizations of the RF coils have been performed. The results were compared to the expected values. A flexible RF coil of 15 mm diameter was then used to perform proton MRI of a saline phantom. When the coil was form-fitted to the phantom surface, a maximum SNR gain of 2 was achieved with respect to identical but plane RF coil. Finally, the flexible coil was used to perform MRI in vivo with high spatial resolution on a mouse using a small animal dedicated scanner operating at 2.35 T.     

结合自适应空间与CRF的遥感影像变化检测

提出了一种结合自适应空间与条件随机场（CRF）的新框架用于高分辨率遥感影像变化检测,解决了两幅影像配准误差造成的噪声和条件随机场产生的过平滑问题。通过加权自适应空间（WAS）获取差异图像消除了因配准误差造成的部分噪声,采用基于形态学重构的FCM聚类方法（MFCM）构建CRF一阶势减少了斑点噪声;引入带光谱—空间约束的模型改进CRF二阶势,进一步提高了算法的抗噪性能并可防止过平滑现象。与现有方法相比,该算法的检测精度、虚检率和漏检率都得到明显改进,同时较好地保留了边缘信息。     

基于COMSOL的磁共振成像双平面梯度线圈的仿真研究

目的：采用COMSOL有限元软件对磁共振成像横向双平面梯度线圈进行仿真分析,为高性能梯度线圈的设计及制作提供技术支持。方法：首先采用改进的目标场方法设计得到梯度线圈绕线的点数据,然后利用AUTOCAD建立三维模型,最后将模型导入COMSOL中,进行电-磁多场耦合模型仿真和结果分析。并且提出结合3D打印技术为复杂梯度线圈的制作提供技术支持。结果：根据设计的不同参数建立不同的梯度线圈模型进行仿真比较,所设计梯度线圈的梯度磁场可以满足非线性度小于5%的应用要求。结论：通过横向双平面梯度线圈三维模型的有限元仿真,可以为梯度线圈的设计和制作提供一定的参考,对优化设计和制作性能更优的梯度线圈具有重要意义。     

中巴地球资源一号卫星多光谱扫描图象质量评价

基于中国资源卫星应用中心提供的中巴地球资源一号卫星红外多光谱扫描仪（IRMSS）4个波段零级图象数据，首先综合运用各种有效方法进行了图象预处理（包括错位纠正、辐射校正、去噪声、清晰化、几何精校正等），然后在此基础上选择图象信噪比、地面分解力、清晰度、辐射精度、反差等5个指标对图象进行了全面的质量评价。研究分析表明，中巴地球资源一号卫生IRMSS图象某些波段的清晰度和反差稍好于TM，但在图象信噪比、地面分解力、清晰度等方面与TM相比尚有差距；通过图象灰度平衡、清晰化和数据融合等处理，中巴地球资源一号卫生IRMSS数据仍有很大的图象改善空间，并在国土资源调查、城市规划等诸多领域有着广阔的应用前景。     

双分量环形磁通门测斜传感器测量原理分析

在地下勘测,钻井探矿等领域,需要测斜仪对钻头的姿态进行精确定位与控制,实时监测地底下钻头的姿态变化。现有的测斜仪通常为三分量磁通门传感器与三分量加速度传感器相结合,其结构复杂,且磁通门传感器与加速度传感器的轴向要求方向一致,因此需要人工调节与算法调节,加大了前期传感器布置与补偿的计算难度。本文研究了新型测斜传感器,采用环形铁芯设计和铁芯不固定的方法,设计了双分量环形磁通门传感器,并通过铁芯与磁通门传感器的敏感轴方向上磁通量之间的角度关系,通过三维坐标轴旋转计算得出测量被测物体的俯仰角等姿态变化。经过试验表明,新型测斜传感器能对物体的姿态角进行精准测量,精度高,且省去了加速度传感器,简化了传感器结构和测量参数,并且简化了角度测量算法与正交度补偿算法。     

一种新的运动磁目标定位算法

给出了一种简单实用的运动磁目标定位算法.基于目标磁偶极子模型下的磁场表达式,推导出了目标相对于传感器的方位角的通用解析表达式,将求解目标方位角的问题转化为求解目标磁场的方向角和两者的偏差角的问题,从而实现利用单个静止的平面四轴磁通门传感器实现目标定位.实验结果表明该方法是切实有效的,而且实时性和可靠性好,估计的方位角的...